Engines supplied with ethanol and/or with a mixture of ethanol and a traditional fuel (gasoline, premium) encounter difficulties when starting at low temperature. Low temperature is understood to mean an (outdoor) air temperature lower than 5° C. (degrees Celsius). Specifically, when the engine is cold and the air temperature is lower than 5° C., it is difficult for the ethanol to combust. These difficulties are reflected in a lengthier or even impossible process of starting the engine when temperatures are particularly low.
One well-known solution involves heating the fuel mixture before it is injected into a combustion chamber. To this end, heating means are positioned on a fuel intake and heat the fuel before it is injected into the combustion chamber. This technique thus makes it possible to improve cold-starting of the engine. However, the time to start the engine (including the pre-heating time) using such a device still remains relatively lengthy, of the order a few seconds, and such a solution additionally has a relatively high cost.
Document FR 2937381, incorporated herein by reference, proposes a method for starting a combustion engine supplied with a first fuel that may contain ethanol. The engine is also equipped with an auxiliary cold-starting system including an auxiliary tank containing a second fuel having a low ethanol content, and a temperature sensor that measures a temperature of a liquid coolant of the engine. Depending on the proportion of ethanol in the first fuel and on the temperature of the liquid coolant, some of the second fuel is introduced into an engine intake in response to the observation of an event preceding a request to start the engine, such as for example unlocking and opening of a driver's door. Thus, when the starting phase is launched, the low-ethanol fuel is present in the combustion chambers, thereby improving the cold-starting of the engine.
Problems with the ability to reproduce cold-starting exist with such devices. Specifically, for example when the low-ethanol fuel tank is empty, cold-starting is difficult. In addition, adding more or less bulky and complex materials to the engine, such as for example a heating element or else a small tank, leads to problems with bulk, but also with compatibility with the surroundings of the engine.